Fuel line Mod Questions- Confused

Let's start with "what do you have," AKA year make model. Frankly no matter what you have you have covered the two options. Tank or neck. Done safely either is OK. I did not drill my tank, but rather used a sharp awl and then a tapered punch, tapping to work it open. This leaves a lip that gives you reinforcement. I put my return up high, just to one side of the sender. If you are not happy with brazing on the tank, doing this on the neck might be an option. "What I did" was drain the tank, plump my CO2 tank off the MIG (I use CO2 straight, not a mix) and ran a BUNCH of CO2 through the tank with the filler cap off.

For "a safety check" (yeah, redneck) I then stuck a piece of tubing into the new tank hole, let it lay outside the body, and put the filler cap on. Took a propane torch and lit the outgass and it would light and go out, etc. After awhile, the outgas stopped trying to light. I let if flow about another 5 minutes, and then got under there, CO2 still going, and brazed (silver brazed) the new tube in place.

USE A BIG TUBE like 3/8 in case someday you want to go EFI. I used 1/4, which was fine for the return filter, but will need to upgrade it at some point for the EFI.

What helped me the most:

The return system (using a Wix return filter), a thick carb isolator, and some guys use wood, and I went to a rear mount electric pump.

What you are fighting is this alcoholized fuel boils easier than the old straight gas did